1. Field of the Invention
The present invention relates to a refrigerant cycle system having first and second evaporators disposed parallel to each other. The refrigerant cycle system is suitable for a vehicle air conditioner having a front air-conditioning unit for controlling air blown toward a front seat side of a vehicle, and a rear air-conditioning unit for controlling air blown toward a rear seat side of the vehicle.
2. Description of Related Art
In recent years, a request of a large-type vehicle such as a minivan is increased. This type vehicle is necessary to have an air conditioner having a large capacity, such as a dual air conditioner. In a refrigerant cycle of the dual air conditioner, both front and rear evaporators are disposed, while a single compressor and a single condenser are used.
In a vehicle dual air conditioner described in JP-A-9-109656, when the air conditioner operates only for a front seat side of the vehicle, an electromagnetic valve for switching a refrigerant flow toward a rear evaporator is forcibly opened for a short time at predetermined intervals, so that refrigerant staying in the rear evaporator is returned into a compressor. However, in a vehicle where an electromagnetic valve for the rear evaporator is not provided for reducing cost of the air conditioner, when a rear air-conditioning unit is stopped, a lubrication oil staying in the rear evaporator does not return to the compressor, and an oil amount returning to the compressor becomes insufficient. As a result, durability of the compressor is deteriorated.